Raphael josia



UNiTn STATES ,ATENT FFICE.

RAPHAEL JOSIA, OF FLORENCE, ITALY, ASSIGNOR TO WILLIAM REY AND C. DE VARIGNY, BOTH OF PARIS, FRANCE.

COMPOSITION FOR TREATING SULPHATE F LIME FOR THE MANUFACTURE OF ARTIFICIAL MARBLE.

SPEGIFICATION forming part of Letters Patent No. 265,510, dated October 3, 1882.

Application filed August 9, 1882. (No specimens.)

To all whom it may concern:

Beitknown thatLRAPHAEL JOSIA, ofFlorence, Kingdom of Italy, have invented or discovered a new and useful Improvement in Compositions for Treating Sulphates of Lime for the Manufacture of Artificial Marble; and I do hereby declare the following to be a full, clear, concise, and exact description thereof.

In an application for Letters Patent of the United States filed March 2, 1882, I have described and made claim to an improved process of treating or preparing gypsum (calcic sulphate or sulphate of lime) in the making of articles of a material which 1 have termed r5 certaldite without pulverization of the gypsum. In said application I described briefly certainot'theconipounds orcompositions which I employ to produce certain effects and the manner of using them, but stated that separate applications would be made for patents for such compositions.

The present application relates to one ofthe compositions so referred to. and it is designed for use in the process herein described in the making of dark-greencertaldite.

In carrying out the process referred to a suitable piece of gypsum (calcic sulphate) is first formed into the desired shape, or approximately such, by the use ofsuitalile well-known 0 tools. The gypsum employed may be the ordinary native gypsum of commerce, though I prefer that which is comparatively pure or free lrom other matters of different composition. Such gypsum is usually obtained hydrated, or

containing a certain percentage of water in its composition; and the second step in the operation has reference to depriving the gypsum under treatment of a considerable part or the wholcofsuch water. Thisisdonebysubjecting 40 it to the action of a gradually-increasing heat,

varying by preference with the size and quality of the material from 260 to 300 Fahrenheit, for about twelve hours, or until the desired partial or complete dehydration is 0b- 5 tained. The length of time as well as the degree of, heat required to effect this result will vary somewhat with the size, character, and purity of the gypsum employed; but the temperature should not exceed 500 Fahrenheit, and both it and the time of exposure should be regulated and limited with reference to securing uniformity of treatment throughout the whole mass or body. This operation may be known to be complete when a fracture ofa test block presents a uniform white color. Any suitable drying or b.: king apparatus may be employed for this purpose, many such being known in kindred branches of the arts; hutit should be of such construction that the mate rial under treatment shall not be brought into direct contact with the fire. When the desired dehydration has been efl'ected the furnace is allowed to cool gradually, in order that I the material under treatment may be cooled gradually; or the material may be removed with due care to prevent breaking and exposure to moisture, and allowed to cool outside thefurnace gradually until it is reduced in temperature sutliciently to permit handling with safety in its subsequent treatment, which is designed to impart to it the desired color or tint and a high degree ofinsolubility and hardness throughout its mass. This stcpinvolves the use of the composition which forms the subject-matter of invention in the present application. This composition is formed of the tollowingelements: water, by weight,two hundred parts; alum, by weight, two parts; logwood, by weight, four parts; sulphate of iron, by weight, two to three parts. 'Theseingre- 8o dients, being mixed in about the proportions named, form a solution which is used as a bath. and to this enda suitable quantityofit is placed in a vessel of proper shape to receivethe article to be treated, which is dipped or immersed in the bath and subjected to its action until the article has acquired the desired degree of hardness and color. The length of time required to effect this result will depend somewhat on the strength of the ingredients composing the bath or solution, the porosity and nature or physical and chemical condition of the article; but usually twelve hours (more or less) will suffice, though to secure uniformity of treatment and of result through the whole 5 body or mass of the article I prefer repeated dippings-two, three, or more-say two or three seconds at first, and increasing gradually to one, two, three, ormore minutes, more or less,

I with dryingintervals oflikeincreasing length [co between dippings, forhalf or three-quarters of an hour or so, after which the article may remain in the bath for twelve hours or so.

\Vhilc I do not limit my invention to any particular theory of chemical or physical reactions involved in the use of this bath as above described, I believe,with my presentknowledge, that the alum held in solution, by taking the place of the molecules of water displaced by the previous dehydrating operation, acts chemically or physically upon the calcic sulphate and renders it more compact, harder, and less soluble, and that it also has a like indurating action upon the impurities or matters of other composition, (carbonates, &c.,) which are usually contained in greater or less quantities in native gypsums. The sulphate of iron employed also aids in this hardening operation, and thereby permits of the successful use of a smaller quantity of alum than would otherwise be required. It also combines with the logwood ot the bath to impart a dark-green color to the article treated, which will be variegated more or less by irregular lines or veins of darker or other shades, due probably to impurities in the caleic sulphate. A beautit'nlly-variegated dark-green color is thus secured, as well as such a degree of hardness, density, and insolubility as renders the article (certaldite) an excellent substitute for marbles, ornamental stones, tiles, &c., in the various uses to which they are applied in the arts.

hen the article has been treated in the bath as above described it is removed and dried by exposure to the sun or to an equivalent furnace-heat for one or two hours, or by ordinary atmospheric exposure for two or three days, when it is ready for polishing, and such other manipulation as may best fit it for its intended use, which may be done by any of the methods practiced in kindred arts.

No claim is made herein to the process set forth, as that, with various modifications of the same, as circumstances may require, forms the subject-matter of the first application herein referred to. Neither do I limit my present invention to the particular way herein described of applying it, though I now believe this way or process to be the best. I also believe the proportions of ingredients which I have named in forming'my improved composition to be the best for the purposes stated, and, among others, to secure a uniform degree of hardness and color throughout the mass of the article. lt'the solution be very strong, thereis great danger of rendering the surface of the article hard very quickly, and thereby preventing proper action of the bath upon the interior substance of the article; or if the solution be very weak too much time is required, and even then a proper degree of hardness, density, and insolubility is not secured; also, by the conjoint action of all the elements of the bath much better results are secured, especially upon native gypsums, than by a solution formed of a part of the elements. For these reasons 1 prefer to employ all the elements of the composition in substantially the proportions named; but such limits, though alfording the best re sults, may be varied or exceeded somewhat and still obtain favorable results under skillful manipulation, and all such modifications employing the elements substantially as herein described in about the proportions set forth I consider as coming within my invention and claim.

I claim as my invention- The composition herein described for treating dehydrated gypsum, consisting substantially of the following elements: water, alum, logwood, and sulphate of iron, in about the proportions set forth.

In testimony whcreofI have hereunto set my hand.

RAPHAEL JOSIA.

Witnesses:

(lumo PAN'IALIONY, 1%. H. WHI'r'rLEsEY. 

